The present invention relates to a chemical feeder, and, more particularly to a chemical feeder which is useful for the controlled dispensing of a chemical into a pipeline transporting a liquid.
Chemical treatment of potable water, including removal of undesirable sulphur ordors, is often necessary. To accomplish this treatment, various devices in the art seek to feed controlled amounts of a water-soluble chemical into a water line or pipeline wherein the pressure is subject to variation. Such a device is our invention described in U.S. Pat. No. 4,548,228, issued Oct. 22, 1985, for a chemical feeder which is satisfactory for applications where water is pumped from a well into a pressure tank wherein the pressure varies between a maximum and a minimum (typically, between 20 to 40 pounds per square inch). In the typical situation, the pump starts at the minimum pressure and stops at the maximum pressure. This pressure variation is used in our above mentioned invention to create a reservoir of compressed air in a pressure tight container, which expands to force the chemical solution into a water line whenever the pressure in the line is less than the pressure in the container.
In providing a chemical feeder for the dispensing of a chemical solution into a pipeline, it is important to provide for easy addition of the chemical to be dispensed, and to provide simple means for preselecting the amount of chemical to be dispensed. It is also desirable to provide a chemical feeder for the dispensing of the chemical solution from a container in applications wherein the pressure in the pipeline is substantially constant, such as in sprinkler systems, irrigation systems and swimming pools, and the chemical solution is forced from the container into the water. It is further desirable to provide a chemical feeder with the capability to dispense chemical in response to either variable pressure or constant pressure in the pipeline.